<html>
  <head>
    <style>
      body {
        margin: 0;
      }
      .container {
        display: flex;
        background-color: lime;
        top: 0;
        bottom: 0;
        position: absolute;
        width: 100px;
      }
    </style>
  </head>
  <body>
    <div class="container"></div>
  </body>
</html>
